title: Carrier-mediated transport of D-ribose by Rhodotorula glutinis.
abstract: The kinetics of D-ribose transport by Rhodotorula glutinis were investigated over a 1 000-fold range of sugar concentrations. Analysis of the saturation isotherm revealed the presence of two carrier systems for D-ribose in the Rhodotorula plasma membrane. These two carriers exhibited Km values of 1.3 and 30 mM. At saturating concentrations of D-ribose, the low Km carrier contributes less than 10% to the total rate of transport. Although D-ribose is metabolized rapidly by Rhodotorula, intracellular free sugar concentrations exceed those in the medium. In addition, the transport of this pentose is inhibited by the proton-conductors, 2,4-dinitrophenol and carbonylcyanide m-chlorophenylhydrazone. These data suggest that Rhodotorula cells are capable of an energy-dependent, concentrative transport of D-ribose.
mesh_terms: D019297:2,4-Dinitrophenol; D001693:Biological Transport, Active / Q000187:drug effects; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004140:Dinitrophenols / Q000494:pharmacology; D007700:Kinetics; D003904:Mitosporic Fungi / Q000378:metabolism*; D012248:Rhodotorula / Q000378:metabolism*; D012266:Ribose / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D004140:Dinitrophenols; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D012266:Ribose; D019297:2,4-Dinitrophenol